The subject matter described herein relates generally to controlling operation of a wind turbine, and more specifically, to controlling operation of a wind turbine based at least partially on upwind measurements from an upwind measurement device.
Wind turbine generators utilize wind energy to produce electrical power. Wind turbine generators typically include a rotor having multiple blades that transform wind energy into rotational motion of a drive shaft, which in turn is utilized to drive an electrical generator to produce electrical power. Each of the multiple blades may be pitched to increase or decrease the rotational speed of the rotor. Pitching a blade refers to rotating the blade to change the angle of attack of the wind on the blade. Pitching toward feather, or feathering the pitch, refers to rotating the blade such that the blade surface is aligned along a direction of the wind speed (i.e., reducing the angle of attack). Pitching a blade toward feather decreases wind energy capture by the blade. Typically, blades are progressively pitched toward feather to counteract increasing wind speed in order to maintain a substantially constant generator speed.
Changes in atmospheric conditions, for example, wind speed, wind turbulence intensity, and wind direction, may significantly influence power produced by wind turbine generators. A power output of a wind turbine generator increases with wind speed until the wind speed reaches a rated wind speed for the turbine. At and above the rated wind speed, the wind turbine generator operates at a rated power. The rated power is an output power at which a wind turbine generator can operate with a level of fatigue to turbine components that is predetermined to be acceptable. At wind speeds higher than a certain speed, or at a wind turbulence level that exceeds a predetermined magnitude, typically referred to as a “trip limit” or “monitor set point limit,” wind turbines may be shut down, or the loads may be reduced by regulating the pitch of the blades or braking the rotor, in order to protect wind turbine components against damage. A static rated power and static trip limits are typically determined during a design stage of the wind turbine and therefore are not dependent upon changing wind conditions that may be present during operation of the wind turbine. A high wind turbulence intensity corresponds to frequently changing wind conditions, which may include frequent and/or strong wind gusts. Wind gusts are sudden, brief increases in the speed of the wind.
Sensors positioned on the wind turbine react to wind conditions as they affect the wind turbine. For example, a wind speed sensor positioned on the wind turbine will measure a wind gust at substantially the same time as the wind gust strikes the rotor blades. Wind turbine operation adjustments are subject to a time lag between measurement of the wind gust and the actual pitching of the blades, and therefore, wind turbine operation adjustments typically are performed at a time after the wind gust has affected wind turbine operation. As a result, the wind gust may cause the rotor speed and/or the output power to exceed a trip limit, before a wind turbine operation adjustment is completed, causing a wind turbine shut down.
Measurements of wind conditions upwind from the wind turbine may be used by a system controller of the wind turbine to determine wind turbine operating commands. A change in wind speed may be measured upwind from the wind turbine, and the pitch of the blades adjusted to compensate for the change in wind speed once the wind reaches the wind turbine. However, wind turbine performance may be reduced in times of high wind turbulence due to oscillations in blade pitch caused by rapid component adjustments. Additionally, a balance between a torque on the rotor created by interaction of the rotor blades and the wind and a generator torque facilitates stable operation of the wind turbine. Blade pitch adjustments may cause an imbalance between the torque on the rotor caused by the wind and the generator torque.